Such an assembly is known from GB 1 442 121. This publication shows a capsule in which the basic body can be slid into the cap along a certain distance in order to realize a releasable closure of the capsule, and wherein it is also possible to slide the cap further into the cap in order to realize a total closure. There is a need for a releasable closure in view of a situation prior to filling the capsule, in which it is common that the basic body and the cap are transported together and are offered to a machine for filling the capsule together. In the filling machine, the basic body and the cap are pulled apart, for example under the influence of a vacuum, after which the filling is supplied, and the basic body and the cap are joined again. In that situation, there is a need for realizing a total closure, wherein it is not possible to separate the basic body and the cap from each other under normal circumstances.
For the purpose of realizing the releasable closure, axial ridges are arranged on an inner surface of the cap, which are extending in a longitudinal direction, and which are adapted to contact an outer surface of the basic body, wherein the cap is retained under the influence of friction between the axial ridges of the cap and the outer surface of the basic body. The connection between the basic body and the cap on the basis of friction can be released by applying forces which are higher than the friction forces, for example vacuum forces.
For the purpose of realizing the total closure, circumferential ridges are arranged on the inner surface of the cap, which are extending over a portion of a circumference of the cap, wherein the basic body has a circumferential area which is adapted to slide over the circumferential ridges and subsequently retain the circumferential ridges. In particular, the circumferential area is realized on the basis of a constriction of the basic body. When the basic body and the cap are slid into each other, the basic body and the cap are being pressed apart somewhat, in a radial direction, until the circumferential ridges are entirely located in the circumferential area. At that moment, the basic body and the cap resume their original shapes, and a form closure is realized, which can not be released under normal circumstances, in particular the circumstances which will further be encountered by the capsule. In particular, the basic body and the cap can no longer be slid from each other, because an outer diameter of a portion of the basic body over which the circumferential ridges should be pulled in that case is larger than an inner diameter of the circumferential edges, at the position of an area of the circumferential ridges located most to an inside. On the basis of this fact, the obtained form closure can also be indicated as snap connection.
For sake of completeness, it is noted that in respect of both the axial ridges and the circumferential ridges, it is true that these are positioned over the circumference of the cap with a certain intermediate space, so that air can escape when the basic body and the cap are being slid into each other.